I am not very familiar with the device, but as the MC13213 reference manual say, the maximum throughput is 250 kbps. It means that the baudrate will depend on the amount of bytes that the application is transmitting, the data processing and the codification of the application. Unfortunately there is nothing to do in order to enhance the SMAC broadcast speed. Remember the MC13213 system is intended to monitoring and control application with a low baudrate needed.
Regards,
Nina